It was two nights to remember for MSNBC, which beat cable news networks’ 800-pound gorilla Fox News Channel among adults 25-54 in primetime on Monday and Tuesday. The surge, fueled by coverage of the secret Mitt Romney tape, peaked on Tuesday, when MSNBC topped Fox News 575,000-526,000 in 25-54 primetime viewers. MSNBC claimed the top program in the demo for the night, Rachel Maddow, which drew a massive 703,000 25-54 viewers, topping perennial victor Bill O’Reilly (682,000), who had Jon Stewart as a guest that night. By Wednesday, the standings went back to they way they have been for years, with Fox News besting MSNBC in the demo (578,000-500,000) and O’Reilly back at No. 1. (In total viewers, Fox News has been consistently the top finisher.)

On the heels of winning the ratings race on Night 1 of the Democratic National Convention, the two-night winning streak this week is sure to give MSNBC a boost of confidence. It showcased the network’s winning combo of Maddow and Lawrence O’Donnell. The media focus has been largely on Maddow because of her virtually unprecedented nightly win Tuesday with a ratings high for 2012. But O’Donnell has had a great week too. Boosted by the big lead-in from Maddow, O’Donnell on Tuesday posted all-time highs in total viewers (1.74 million) and all key demos, including 24-54 (535,000).

What’s more, after finishing No. 2 in 25-54 on Tuesday behind Maddow and O’Reilly, O’Donnell actually carried the flag for MSNBC on Wednesday, finishing as the network’s top program (531,000 in 25-54) behind Fox News’ Sean Hannity (643,000) and O’Reilly (633,000) and ahead of Maddow (521,000). O’Donnell was down only 4,000 viewers (0.7%) from Tuesday, despite his lead-in, Maddow, dropping 26%. It was O’Donnell’s second-highest 25-54 viewership ever only behind the Tuesday telecast. And he beat his biggest competitor at 10 PM, Fox News’ Greta Van Susteren, every night Monday through Wednesday, news that raises concern for the veteran Fox News anchor.